Correct me if I'm wrong, but I was under the impression that a .357Mag will not chamber in a .38Spec chamber, or at least the nose of the bullet would stick out and the cylinder wouldn't close. I've never heard of a non-revolver chambered in .38Spc, but even there were lever guns chambered in .38Spc I'd think that for safety reasons the chamber would be shallow enough so the .357Mag couldn't fit because it'd hit the throat of the chamber.

Mike